The present invention generally relates to image projection and television viewing systems. More particularly, the present invention relates to an apparatus for enabling a centrally located video image to be viewed substantially simultaneously by an audience surrounding the image through a 360° span.
The general problem in the display of a picture print, a television image or a projection onto a screen is that the picture is best viewed when the viewers line of sight is precisely normal to the plane of the picture. Traditional television sets are relatively flat and square. These television sets must be positioned strategically within a room so that they are easily viewed by the viewers. When a viewer is not positioned directly in front of the television set, the best possible viewing angle is not achieved, or a viewing angle is not achieved at all. Thus, it is difficult for several people wishing to view a picture simultaneously from varied locations.
Placing four television sets back-to-back does not create a 360° angle, as in reality there are only four points or four direct viewing angles in which the viewer has the proper angular view of the television. Furthermore, placing four existing television sets back-to-back in an attempt to create a 360° viewing angle is rather costly as four television sets must be purchased.
Another solution is to simply mount a picture on a rotating pedestal which will slowly rotate over 360°, permitting several people surrounding the pedestal to eventually view the picture in a line of sight normal to the plane of the picture. Such systems are often used in advertising displays within large areas such as railroad stations and the like. A problem with such an arrangement is that the rotation of the picture must be relatively slow in order to permit the various viewers to have an opportunity to study the picture. Such a slow rotation means that essentially only a few people at a time are viewing the picture while others out of the line of sight must wait until the picture comes into view.
There are many instances in which several people may wish to view a picture or displayed data simultaneously and continuously so that they can all carry on a meaningful discussion concerning the displayed information. For example, during business meetings a group of executives typically sit around a conference table, an arrangement which does not readily enable information presented to be displayed to all in attendance. A great benefit would be realized if a means centrally located on the table were available which would permit everyone present to examine a picture or projected substantially simultaneously. For example, the necessity of passing among the members of the group pictures to be successively viewed would be avoided. In addition, the ability to display data through a 360° range would prevent members from looking at a series of pictures out of order, a potential problem if duplicate sets of pictures were to be provided to each individual member.
Another drawback associated with conventional display systems is that special consideration must be given to the positioning of the display within its environment because, typically, conventional display systems, such as a television, cannot be viewed from the rear or extreme sides. Thus, the area within which a viewing audience can be accommodated is limited to locations with suitable sight lines. As a result, use of the space available around the display system is often limited by the presence of blind spots. Moreover, the positioning of furniture within the room can disadvantageously be dictated by a need to provide clear sight lines to a television or the like.
In an attempt to overcome the viewing limitations associated with conventional displays, 360° viewing systems have been developed, examples of which are shown in U.S. Pat. Nos. 3,976,837; 4,901,140; 4,943,851 and 4,979,026, the contents of which are incorporated herein by reference.
Such systems disclosed in these patents suffer from a visually perceptible blur at the edge of the projected image as it rotates past the viewer's line of sight. It was found that blurring of the image could be reduced by providing a slit in front of the projection screen, which rotated together with the screen, although only a very small fraction of the projected image passed through the slit to reach the eye of the observer. Thus, the apparent screen brightness was found to be fifty to one-hundred times less than the brightness of the stationary screen.
U.S. Pat. No. 6,072,545, the contents of which are incorporated herein by reference, discloses a video image rotating apparatus designed to minimize the visible blur at the edge of a projected video image and increase the apparent brightness of the rotational screen. The apparatus of the '545 patent presents a projected image upon a rear projection screen that is rotated extremely rapidly about a vertical axis which exactly bisects the picture in the vertical plane. While substantially eliminating blurred edges and intensifying the perceived brightness of the image, the apparatus requires a plurality of three to four mirrors to erect an image from its original horizontal position to the vertical position of the projection lens screen. The rotation of the three or more erecting mirrors requires a relatively large area behind the lens screen. This limits the proportion of the final image size with respect to the overall drum size of the apparatus. The three or more mirror erection system also requires precise placement of the mirror system relative to each other in the optical pathway in order to project an image to the rear projection lens screen.
The apparatus of the '545 patent also incorporated an electronic image rotation system for electronically rotating the images produced by light valves in synchronization with rotation of the rear projection screen. Such electronic rotation system requires a fairly complex synchronization separator circuit, memory, and an algorithm-further complicating the device and adding increased costs.
Accordingly, an improved 360° viewing system is needed that is simpler in design so as to require less space and expense while eliminating visible blurs at the edges of the projected video image and providing sufficient screen brightness. The present invention fulfills these needs and provides other related advantages.